[.NET] Benchmark - Count() vs Any()

요약

• 특정 조건에 대한 값이 존재하는지 유무를 따질 땐, Count() 보단 Any()를 사용하는 것이 좋다.
• 조건은 Where()로 처리하는게 더 유리하다.

테스트코드

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Jobs;
using BenchmarkDotNet.Running;

BenchmarkRunner.Run<CountVsAny>();

[MemoryDiagnoser]
[SimpleJob(runtimeMoniker: RuntimeMoniker.Net60)]
[SimpleJob(runtimeMoniker: RuntimeMoniker.Net70)]
public class CountVsAny
{
    public int[] items;
    public CountVsAny()
    {
        items = Enumerable.Range(0, 1000).ToArray();
    }

    [Benchmark]
    public bool IsExistsUseCount()
    {
        return items.Count() != 0;
    }

    [Benchmark]
    public bool IsExistsUseAny()
    {
        return items.Any();
    }

    [Benchmark]
    public bool IsItem100ExistsCount1()
    {
        return items.Count(x => x == 100) != 0;
    }

    [Benchmark]
    public bool IsItem100ExistsCount2()
    {
        return items.Where(x => x == 100).Count() != 0;
    }

    [Benchmark]
    public bool IsItem100ExistsAny1()
    {
        return items.Any(x => x == 100);
    }

    [Benchmark]
    public bool IsItem100ExistsAny2()
    {
        return items.Where(x => x == 100).Any();
    }
}

벤치마크 환경

BenchmarkDotNet=v0.13.3, OS=Windows 11 (10.0.22000.1335/21H2)
Intel Core i7-6700 CPU 3.40GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
.NET SDK=7.0.101
  [Host]   : .NET 6.0.12 (6.0.1222.56807), X64 RyuJIT AVX2
  .NET 6.0 : .NET 6.0.12 (6.0.1222.56807), X64 RyuJIT AVX2
  .NET 7.0 : .NET 7.0.1 (7.0.122.56804), X64 RyuJIT AVX2

벤치마크 결과

Method	Job	Runtime	Mean	Error	StdDev	Median	Gen0	Allocated
IsExistsUseCount	.NET 6.0	.NET 6.0	12.66 ns	0.305 ns	0.889 ns	12.39 ns	-	-
IsExistsUseAny	.NET 6.0	.NET 6.0	12.81 ns	0.288 ns	0.413 ns	12.78 ns	-	-
IsItem100ExistsCount1	.NET 6.0	.NET 6.0	7,031.76 ns	138.620 ns	198.804 ns	7,025.99 ns	0.0076	32 B
IsItem100ExistsCount2	.NET 6.0	.NET 6.0	2,485.07 ns	49.684 ns	72.826 ns	2,463.69 ns	0.0114	48 B
IsItem100ExistsAny1	.NET 6.0	.NET 6.0	698.90 ns	13.834 ns	20.706 ns	695.52 ns	0.0076	32 B
IsItem100ExistsAny2	.NET 6.0	.NET 6.0	323.11 ns	5.399 ns	6.428 ns	324.02 ns	0.0114	48 B
IsExistsUseCount	.NET 7.0	.NET 7.0	10.38 ns	0.244 ns	0.358 ns	10.45 ns	-	-
IsExistsUseAny	.NET 7.0	.NET 7.0	13.35 ns	0.300 ns	0.613 ns	13.25 ns	-	-
IsItem100ExistsCount1	.NET 7.0	.NET 7.0	7,276.72 ns	143.112 ns	218.547 ns	7,234.79 ns	0.0076	32 B
IsItem100ExistsCount2	.NET 7.0	.NET 7.0	3,471.19 ns	69.154 ns	67.918 ns	3,484.87 ns	0.0114	48 B
IsItem100ExistsAny1	.NET 7.0	.NET 7.0	733.56 ns	14.655 ns	21.018 ns	725.20 ns	0.0076	32 B
IsItem100ExistsAny2	.NET 7.0	.NET 7.0	329.38 ns	6.588 ns	7.586 ns	331.38 ns	0.0114	48 B

• Mean, Error, StdDev, Median : 낮을 수록 빠름 (=낮을수록 좋음).
• Gen0, Allocated : 낮을 수록 메모리 사용 적음 (=낮을수록 좋음)